Dancing Eye syndrome

Background

Dancing eye syndrome (DES) or Opsoclonus myoclonus syndrome
(OMS) is a very rare neurological condition which usually develops
in the second or third year of life. The syndrome gets its name
from the very unusual and characteristic eye movements, which are
almost always present.

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What are the symptoms?

The main features of the syndrome are ataxia (unsteadiness),
myoclonus (jerky movements of the trunk and limbs), opsoclonus
(rapid involuntary eye movements in all directions) and usually
irritability with sleep disturbance. As with many other conditions,
there is considerable variation in severity.

Most children develop the condition in the second or third year
of life, but rarely it may occur earlier or later in childhood.
There is also an adult variant of the condition.

What are the causes?

In children, the condition may occur with no clear trigger, or
it may follow a viral illness. In about 50% of cases, it may be
associated with a tumour called a neuroblastoma. Whenever DES/OMS is
diagnosed, it is therefore important that a detailed series of
tests are undertaken to make sure that neuroblastoma is not
present.

If neuroblastoma is present it is usually, but not always, a
benign (non-cancerous) variant of the tumour. Treatment of the
neuroblastoma, whilst important in its own right, does not appear
to alter the outcome of DES/OMS.

Because of the association with preceding infection and with
neuroblastoma and the frequent response of the condition to
treatments which modify the immune system (immunomodulatory
therapies), it is thought likely that DES/OMS is the result of an
immune or allergic cross-reaction in the brain, though there is no
definite proof of this to date.

How is it diagnosed?

The diagnosis is based on the four characteristic clinical
features:

eye movements (which are sometimes fleeting and difficult to
spot)

unsteadiness and jerkiness

irritability and sleep disturbance

neuroblastoma.

The criteria for making a diagnosis have been formulated as
being at least three of these four features in a child. Because it
is very rare, many doctors are unfamiliar with the condition and
the diagnosis can sometimes be delayed.

How is it treated?

The treatments used for DES/OMS are those used to suppress the
immune response. Steroids given by mouth or injection have been the
main drugs used as they dampen down the effect of the immune
system. Other treatments which modify the immune system may also be
used; these include cyclophosphamide, rituximab, intravenous
immunoglobulin and azathioprine. Large-scale research trials in
Europe and the USA are aimed at improving the treatment
options.

The longer term outcome of this condition is very variable. A
very few children fully recover very quickly without treatment.
Others respond to treatment partially or completely. More severely
affected children often have longer-term problems with learning,
coordination, behaviour and sleep which need careful assessment and
treatment in their own right.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
There is no indication that the condition runs in families
although immune-related conditions, such as thyroid disease and
rheumatoid arthritis, are more common in families with a child
affected by DES/OMS.